The trees tower in the sky, while the mosses carpet the forest floor. Mosses, like the first plants, are restricted to life near the ground because they lack vascular system. Only with a vascular system can these trees transport sugars, nutrients, and water up and down their tall trunks. The evolution of the vascular system was a big step in the evolutionary history of plants.

Vascular Seedless Plants

For these plants, the name says it all.
Vascular seedless plants
have vascular tissue but do not have seeds. Remember that vascular tissue is specialized tissue that transports water and nutrients throughout the plant. The development of vascular tissue allowed these plants to grow much taller than nonvascular plants, forming ancient swamp forests. Most of these large vascular seedless plants are now extinct, but their smaller relatives still remain. Vascular tissue includes xylem, which transports water from the roots to the rest of the plant; and phloem, which transports sugars and nutrients from the leaves throughout the plant.

Clubmosses

Clubmosses
are so named because they can look similar to mosses (
Figure
below
). Clubmosses are not true mosses, though, because they have vascular tissue. The “club” part of the name comes from club-like clusters of sporangia found on the plants. One type of clubmoss is called the "resurrection plant" because it shrivels and turns brown when it dries out but then quickly turns green when watered again.

Clubmosses can resemble mosses; however, clubmosses have vascular tissue, while mosses do not.

Ferns
are the most common seedless vascular plants (
Figure
below
). They usually have large divided leaves called fronds. In most ferns, fronds develop from a curled-up formation called a fiddlehead (
Figure
below
). The fiddlehead looks like the curled decoration on the end of a stringed instrument, such as a fiddle. Leaves unroll as the fiddleheads grow and expand. Ferns grow in a variety of habitats, ranging in size from tiny aquatic species to giant tropical plants.

Ferns are common in the understory of the tropical rainforest.

The first leaves of most ferns appear curled up into fiddleheads.

Horsetails

Horsetails
have hollow, ribbed stems and are often found in marshes (
Figure
below
). Whorls of tiny leaves around the stem make the plant look like a horse's tail, but these soon fall off and leave a hollow stem that can perform photosynthesis. This is unusual since photosynthesis most often occurs in leaves. The stems are rigid and rough to the touch because they are coated with a scratchy mineral. Because of their scratchy texture, these plants were once used as scouring pads for cleaning dishes.

Horsetails are common in marshes.

Whisk Ferns

Whisk ferns
have green branching stems with no leaves, so they resemble a whisk broom (
Figure
below
). Another striking feature of the whisk ferns is its spherical yellow sporangia.

Whisk ferns have yellow sporangia and no leaves.

Vocabulary

club moss
: Vascular seedless plant that looks similar to the nonvascular moss, but with true roots, stems, and leaves.